This invention relates to a connector for electrically connecting a high voltage cable to an electrical apparatus bushing with a threaded opening.
In high voltage electric utility circuits, especially in underground systems, it is necessary to make connections between the high voltage cables and various electrical apparatus, such as padmounted switchgear and padmounted transformers. Typically, the connection is made through the use of a connector on the end of the cable and a bushing on the electrical apparatus. A secure connection between the connector and the bushing is necessary.
Because it is hard to maneuver the stiff high voltage cable while attempting to connect the cable connector to the bushing, it is difficult to accomplish the connection.
Many different methods have been used for securing the connector to the bushing. This invention relates to such connections which utilize a threaded connecting member housed in the connector, which connecting member is threaded into a threaded opening in the bushing by rotating the threaded member. Examples of connectors including such threaded connecting members include U.S. Borgstrom Pat. No. 4,202,591 and U.S. Sankey et al Pat. No. 3,883,208; which is hereinafter incorporated herein by reference.
A problem encountered with these connector designs has been in getting the threaded connecting member secured in the threaded bushing opening without stripping the threads on the connecting member. Although some connector designs have used a connecting member including a threaded portion having a major diameter and a minor diameter and a non-threaded lead portion, the length of the lead portion was shorter than the length of the threaded portion, and the diameter of the lead portion was substantially less than the minor diameter of the threaded portion. As a result, there was a loose fit between the lead portion and the bushing threaded opening. Further, the threaded portion did not have a blunt lead. These factors generally contributed to the thread stripping problem.